Telescoping slot nozzle

Abstract: Telescoping slot nozzles (10) for use with a rail assembly (45) are disclosed. Each nozzle includes a fixed portion (5) and at least one telescoping portions (12) slidably guided in the fixed portion. Metal-to-metal contact in the nozzle is avoided, thereby allowing the nozzles to operate at high temperatures. The configuration of the nozzle discharge opening (6,6') can be easily modified to form an air knife, depending upon the particular application. Each nozzle is independent of the others, thereby facilitating retrofitting existing ovens and maintenance of individual nozzles.

Description: In the production of oriented film for example, the film web is transported through an oven that will heat and/or cool the web. A typical oven consists of slot nozzles which provide convective heat transfer by air impinging on the web, and mechanical means (such as a tenter) for transporting and stretching the web. The tenter consists of clips that clamp to the edge of the web and rails that guide the clips through the oven. The distance between rails is typically adjustable to allow for the production of different width webs and different stretch rates. In order to allow for the adjustment of the rails depending on the film web width, the slot nozzles, which are arranged on either side of the plane of travel of the web, are positioned above and below the rails. As a result of the rails between the sets of nozzles, nozzle-to-web distances are not at the optimum, sometimes being as much as 41 cm (16 inches) apart. As the nozzle-to-web distance increases, the heat transfer coefficient and uniformity decrease, thereby resulting in an inefficient oven and poorer quality film. In response to problems similar to the foregoing, US-A-2270155 and US-A-2495163 disclose the use of nozzles having variable lengths according to the width of a cloth being treated. The nozzles include a fixed part corresponding to the minimum width of the cloth to be treated, and end extensions slidably mounted on the fixed part, which are responsive to the movements of the chain guide rails. As a result, the nozzles need not be located above and below the top and bottom rails, respectively, but instead can be located in the same planes as the rails. The present invention is directed to an improved telescoping slot nozzle for tenter frames as hereinafter described. SUMMARY OF THE INVENTION The problems of the prior art have been solved by the present invention, which provides telescoping slot nozzles for use with a rail assembly. The present invention provides a telescoping nozzle characterised by the features of claim 1. The configuration of the nozzle discharge opening can be easily modified to form an air knife, depending upon the particular application. Each nozzle is independent of the others, thereby facilitating retrofitting existing ovens and maintenance of individual nozzles. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a front cross-sectional view of a telescoping nozzle in accordance with a first embodiment of the present invention; Figure la is an enlarged view of the portion of figure 1 encircled; Figure 2 is a side view of the telescoping nozzle of Figure 1; Figure 3 is a side view of the telescoping nozzles of the present invention shown attached to a rail assembly; and Figure 4 is a front cross-sectional view of a telescoping nozzle in accordance with a second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION Turning now to Figure 1, there is generally shown a telescoping slot nozzle 10. The nozzle 10 has a pair of slot nozzle side channel plates 6, 6' which are bent at their upper and lower ends in a U-shape so as to hold wear strips 62, 63, 66 and 67, preferably made of Teflon, and to form a track for purposes to be discussed below. The side channel plates 6, 6' are affixed to a slot nozzle stiffener base 7 via a plurality of studs 2, 2' provided on the side channel plates 6, 6'. A central channel member 5 for return air is substantially centrally located in the nozzle 10, and includes a plurality of guide shaft-receiving members 8 having apertures 9. The channel member 5 is substantially U-shaped, having a pair of top flanges 21, 22 dimensioned so as to receive therebetween top support 100 (best seen in Figure la). Each air discharge slot is defined by an adjustable slot plate 3 having a main body extending over the channel member 5 and including side bends 23, 24 which terminate in flange portions 25, 26, respectively. The position of the slot plate 3 is adjustable during assembly to modify the dimensions of the air discharge nozzle slot 30 or 30', and is then sandwiched between two pieces of sheet metal 3a, 3b which also sandwich a central sheet 3c and is secured in place (such as with bolts). As best seen in Figure 1a, a space "A" is shown between slot plate 3 and the central sheet 3c allowing for rectilinear adjustment of slot plate 3. Slot plate 3 has a plurality of spaced slotted holes to receive the securing bolts which clamp it in place once the rectilinear adjustment is completed. The nozzle gap alongside the channel member 5 is defined between the slot plate 3 and side channel plates 6, 6' to form the respective fixed air discharge slot 30, 30'. One suitable dimension for each of fixed slots 30, 30' is 9.9 mm (0.39 inches), although it will be understood by those skilled in the art that the air slot size can vary considerably depending upon the particular requirements of the application. The telescoping portion of nozzle 10 includes a U-shaped sliding exterior channel member 12 coupled to sliding external extension channel plates 16 and 16' via an end plate 13 (shown in Figure 2). Sliding exterior channel member 12, also substantially U-shaped, slidingly fits about channel member 5 as shown and includes flange portions 27, 28 bent away from portions 21 and 22, respectively, of channel member 5. The flange portions 27, 28 of sliding exterior channel member 12 are confined within the spaces defined by the exterior of side walls 5a, 5b of the channel member 5 and the bent portions 23, 24 of the slot plate 3. Sliding exterior channel member 12 includes a centrally located guide shaft 17 (Figure 2) extending longitudinally in said sliding exterior channel member 12 and affixed at one end of the base portion 12a of the sliding exterior channel member with a holding bracket 18 so that the guide shaft 17 is in the same plane as the apertures 9 of guide shaft-receiving members 8a, 8b affixed to the channel member 5. The guide shaft 17 is of a suitable diameter so as to be slidingly received by said aperture 9, and is preferably longer than the length of the sliding exterior channel member 12. Preferably at least two guide shaft-receiving members 8a, 8b are provided for each guide shaft 17. Sliding external extension channel plates 16, 16' and the sliding exterior channel member 12 are mounted on a U-shaped end plate 13 (Figure 2) so that two air discharge slots 30, 30' are formed therebetween to slidingly receive the side slot nozzle channel plates 6, 6' and through which slots air is expelled so as to impinge upon the web. A suitable air discharge slot width for the telescoping portion is 12.45 mm (0.49 inches), although it again will be understood by those skilled in the art that the width can vary considerably depending upon the particular application. The slot width of the telescoping portion defined by the sliding exterior channel member 12 and the sliding external extension channel plates 16, 16' is slightly larger than the fixed slot width defined by the channel member 5 and the side channel plates 6, 6', since the telescoping portion fits within the framework of the fixed portion and therefore must accommodate its dimensions. With particular reference to Figure 2, where like numerals correspond to elements previously described, nozzle plate cover 1 includes a plurality of studs for coupling of the nozzle to a header assembly 40 (Figure 3). Gasket plate covers 4 holds a Teflon-covered fibreglass gasket 41 in place as shown. Turning now to Figure 3, where like numerals correspond to elements previously described, nozzle 10 is shown coupled to header assembly 40 and tenter rail assembly 45. A right-angle bracket 42 is bolted to each side of nozzle 10 and to a telescoping nozzle support tube 44, preferably made of aluminium. All of the nozzles are coupled together by the support tube 44, although each nozzle can be removed individually. This is highly advantageous in the event of any particular nozzle or nozzles needing to be replaced, cleaned, modified, etc. Each support tube 44 is connected to a guide rod assembly 43 of rail assembly 45. All connections along the tube are slotted to allow the rails to move angularly for repositioning. It will be readily appreciated by those skilled in the art that as the tenter rail assembly 45 as depicted in Figure 3 moves laterally in accordance with the particular width of the web 99 being treated, by being held by clips (not shown) on the rail assembly, it carries with it the telescoping portions of nozzle 10. One important aspect of the present invention is the absence of any metal-to-metal contact in the nozzle 10. As a result, the nozzles are capable of efficient operation up to temperatures of about 260°C (500°F). To this end, Teflon or similar means is used between sliding metal surfaces to reduce friction and to minimize heat transfer therebetween. For example, flange portions 27, 28 of sliding exterior channel members 12 are covered with Teflon wear strips 60, 61, as are the inner portions of each slot nozzle side channel plate 6, 6' that function as a track for sliding exterior extension channel plates 16, 16', as shown by elements 62-67 in Figure 1. Elements 64 and 65 in particular are a Teflon-coated fibreglass cloth gasket that is sewn to a stainless steel hollow core mesh. The Teflon-coated fibreglass cloth gasket is placed between the return air channel 5 and the exterior channel members 12. This gasket prevents air leakage and takes up any inconsistencies in manufacturing. The minimum and maximum dimensions of the telescoping slot nozzle of the present invention are variable, depending upon the particular tenter system for which they are designed. The only limitation in these dimensions is that the sum of the dimensions of the telescoping portion has to be less than the dimensions of the fixed portion. Figure 4 illustrates a second embodiment of the present invention, where like numerals correspond to elements previously described. In this second embodiment, the configuration of one of the nozzles is in the form of an air knife. Specifically, one side of slot plate 103 includes an angled side bend 124 terminating in flange portion 126. A corresponding angled portion 106a' is formed on air bar channel side 106' to define with angled side bend 124 air knife 200. The slot plate 3 is adjustable during assembly to modify the dimensions of the air knife or of the nozzle gap formed on the other side by slot nozzle side channel plate 6 and side bend 23, or both. It will be readily appreciated by those skilled in the art that one or both discharge openings can be designed as air knives.

Claims: A telescoping nozzle for heating, cooling or drying a web (99), comprising a fixed nozzle-defining portion (5, 6, 6') and a slidable exterior telescoping portion (12, 16, 16') characterized in that (a) said fixed portion is defined by a substantially centrally located inner channel member (5) fixed relative to a pair of side channel plates (6, 6') and a top slot plate (3) on said inner channel member, said top slot plate (3) defining with each of said side channel plates (6,6') a pair of fixed discharge gaps (30, 30'); and in that (b) said telescoping portion is defined by a sliding exterior channel member (12) dimensioned to slide about said inner channel member (5), and a pair of sliding exterior extension plates (16, 16') fixed relative to said sliding exterior channel member (12), and dimensioned to slide about a respective said side channel plate (6 or 6'), said exterior channel member (12) defining with each of said extension plates (16, 16') an air discharge slot at the telescoping portion. The telescoping nozzle of claim 1, wherein said sliding exterior channel member (12) comprises at least one guide shaft (17), and wherein said inner channel member (5) comprises at least one guide shaft-receiving member (8) for slidingly receiving said guide shaft (17), thereby allowing said telescoping portion (12, 16, 16')to slide within said fixed portion (5, 6, 6'). The telescoping nozzle of claim 1 or claim 2, wherein said sliding exterior channel member (12), said inner channel member (5), said exterior extension channel plates (16, 16') and said side channel plates (6, 6') are formed of metal, and further comprising means between said exterior channel member (12) and said inner channel member (5), and between said exterior extension plates (16, 16') and said side channel plates (6, 6') to eliminate metal-to-metal contact. The telescoping nozzle of any one of claims 1 to 3, characterized in that said side channel plates (6, 6') are coupled to said inner channel member (5) by a stiffener base (7). The telescoping nozzle of any one of claims 1 to 4, characterized in that at least one of said fixed (30, 30') and one of said telescoping discharge gaps are shaped to form an air knife. A tenter system in a housing, comprising a rail assembly (45) having a plurality of clips for securing to a web and guiding said web through said housing; characterized by a plurality of telescoping slot nozzles (10) according to any one of claims 1 to 5 removably affixed to said rail assembly. The tenter system of claim 6, characterized in that each of said slot nozzles is independent of the others.

Inventors: SEROOGY PAUL G, SEROOGY, PAUL G.
Applicants: MEGTEC SYS INC, MEGTEC SYSTEMS, INC.
Application year: 1994
Main classification: D06B1
IPC codes: D06B1, F26B3, D06C7, B05B1, B29C55